1. Field of the Invention
The present invention generally relates to a backlight module for a liquid crystal display (LCD), and in particular to a backlight module having a heat dissipation structure for removing heat induced by electromagnetic radiation emitted by lamps of the LCD.
2. The Related Art
A liquid crystal display (LCD) comprises a liquid crystal panel arranged in association with a backlight module in which light sources are arranged to project light through the liquid crystal panel for formation of images on the liquid crystal panel. FIG. 6 of the attached drawings shows a conventional backlight module, which is generally designated with reference numeral 10, comprising a casing 11 in which lamps 12 are mounted. A light guide plate 13, a light diffusion plate 14 and a protection plate 15 are stacked in sequence and mounted to the casing 11 in front of the lamps 12 whereby light emitted by the lamps 12 transmits through the light guide plate 13, the light diffusion plate 14 and the protection plate 15.
The lamps 12 of the conventional device are arranged substantially on the same plane and spaced from each other. The distance between adjacent lamps 12 induces a dark strip that leads to non-uniform distribution of brightness over the whole panel. In addition, the great number of lamps 12 mounted inside a limited space within the backlight module 10 causes a serious problem of heat that is generated by the lamps 12 during their operation.
A triangular structure comprised of a prism arranged between adjacent lamps 12 has been proposed to alleviate the non-uniform brightness issue. However, the issue of heat dissipation is not overcome yet.
Thus, it desired to have a backlight module for LCD to overcome the heat problems, while providing uniform brightness.
An object of the present invention is to provide a backlight module comprising air passages formed by side walls made of heat conductive material and vent holes for formation of air flow through the air passages to effectively remove heat from the backlight module.
Another object of the present invention is to provide a backlight module comprising a heat dissipation structure having a triangular configuration for both removal of heat and re-direction of light to provide uniform distribution of the light.
A further object of the present invention is to provide a backlight module capable of effectively removing heat therefrom while maintaining structural strength and stability.
To achieve the above objects, in accordance with the present invention, there is provided a backlight module for liquid crystal display, comprising a casing having a bottom wall and a circumferential side wall extending from the bottom wall to define an open top. A light guide plate is attached to the side wall and spaced from the bottom to define an interior space therebetween. A light diffusion plate and a protection plate are respectively mounted to the top opening of the casing. A plurality of lamps are arranged in the interior space and spaced from each other. First vent holes are defined in the side wall of the casing to allow air to flow in and out of the interior space for removing heat generated by the lamps. Second vent holes are defined in the side wall and are paired of which the second vent holes are opposite to each other. A triangular channel is formed between the second vent holes of each pair by two inclined side walls. Air is allowed to flow into the channel via one of the second vent holes, through the channel and eventually leaving the channel via another second vent hole. The air flowing through the channel removes heat induced on the side walls by radiation of the lamps. The side walls of each channel, which have reflective surfaces, are arranged to reflect light from the adjacent lamps toward the light guide plate for uniformly distributing the light over the light guide plate.